KR100638871B1 - Light emitting diode package and method for manufacturing the same - Google Patents

Abstract

An LED package is provided to greatly reduce fabricating cost of an LED package while embodying an LED package with high reliability by using a glass junction layer having excellent junction strength. A mounting part(20) for an LED device(108) and an interconnection conductor(102a,102b) are formed on the upper surface of a ceramic substrate(101). The LED device is electrically connected to the interconnection conductor, mounted on the mounting part. A metal reflection plate(104) is bonded to the outer circumferential part of the upper surface of the substrate to surround the mounting part wherein the inner circumferential surface of the metal reflection plate is made of a reflection surface(104b) for reflecting the light emitted from the LED device. The metal reflection plate is bonded to the ceramic substrate by using a glass bonding layer including PbO, SiO2, B2O3 and TiO2. The interconnection conductor is made of Ag or a conductor including Ag as a main component. The ceramic substrate is made of a ceramic material including Al2O3 or AlN.

Description

LIGHT EMITTING DIODE PACKAGE AND METHOD FOR MANUFACTURING THE SAME

1 is a cross-sectional view of a light emitting diode package according to the prior art.

2 is a cross-sectional view of a light emitting diode package according to an embodiment of the present invention.

3 is a cross-sectional view of a light emitting diode package according to another embodiment of the present invention.

4 is a cross-sectional view of a light emitting diode package according to another embodiment of the present invention.

5 is a cross-sectional view of a light emitting diode package according to another embodiment of the present invention.

6A to 6E are cross-sectional views illustrating a method of manufacturing a light emitting diode package according to an embodiment of the present invention.

7 is an optical micrograph showing a cross section of an interface portion of a ceramic substrate and a glass bonding layer of a light emitting diode package manufactured according to the present invention.

<Description of the symbols for the main parts of the drawings>

100, 200, 300, 400: light emitting diode package

101: ceramic substrate 102a, 102b: wiring conductor

104: metal reflecting plate 104a: through hole

104b: Reflective surface 105: Translucent molding part

108: LED element 109: bonding wire

111: metal layer 113: glass bonding layer

120: transparent cover 20: mounting portion

The present invention relates to a light emitting diode package and a method of manufacturing the same, and more particularly, to a high reliability light emitting diode package having excellent mechanical strength and thermal stability and a method of manufacturing the same.

Recently, light emitting diodes (hereinafter, also referred to as LEDs) have been used as light sources of various colors. In particular, as the demand for high-power, high-brightness LEDs for lighting LED lights increases, a lot of heat is generated in the LED device. To prevent deterioration of the device's characteristics and shortening its life, heat generated in the LED device (LED chip) must be effectively released from the LED package. Therefore, efforts are being made to effectively dissipate heat generated from LED devices in high power LED packages. For example, Korean Laid-Open Patent Publication No. 2003-0053853 discloses a light emitting diode package having a ceramic substrate and a metal reflector.

1 is a side cross-sectional view showing an example of a conventional LED package. Referring to FIG. 1, the LED package 10 includes a substrate 11 made of ceramic material and a reflective plate 14 made of metal. The through plate 14a is formed in the reflecting plate 14, and the inner surface of the through hole 14a forms the reflecting surface 14b. The reflecting plate 14 is bonded onto the substrate 11 by Au-Sn solder 13. The LED element 18 is connected to the mounting portion 2 on the upper surface of the substrate 11 and electrically connected to the wiring conductors 12a and 12b by wire bonding by the wire 19. In the through hole 14a, a translucent molding member 15 such as a silicone resin is provided to wrap the LED element 18.

According to the above conventional technique, Au-Sn solder 13 is used to bond the reflecting plate 14 to the substrate 11. This Au-Sn solder 13 provides sufficient bonding strength, but is very expensive because gold (Au) is used as the main material. Therefore, there is a problem that the manufacturing cost of the LED package is greatly increased. In addition, since the Au-Sn solder 13 has a larger thermal expansion coefficient (coefficient of thermal expansion of 15 ppm / K or more) than the ceramic substrate 11 or the metal reflecting plate 14, thermal stability is not excellent. Therefore, during the cooling after the high temperature heating, a large stress is generated at the joint between the Au-Sn solder 13 and the other members 11 and 14, and the joint strength thereof may be weakened.

As another method of bonding the reflecting plate 14 to the substrate 11, there is a method of using a polymer resin such as Si resin or epoxy resin as the bonding layer. In addition, there is a brazing method for bonding the reflector plate 14 and the substrate 11 by applying pressure at a high temperature. However, when the polymer resin bonding layer or the brazing is used, the bonding strength is low, so that the bonding between the reflector 14 and the substrate 11 may be easily broken due to external impact.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly reliable light emitting diode package having excellent bonding strength between a reflecting plate and a substrate and reduced manufacturing cost.

In addition, another object of the present invention is to provide a method of manufacturing a light emitting diode package that can implement excellent bonding strength between the reflecting plate and the substrate, and can reduce the manufacturing cost.

In order to achieve the above technical problem, a light emitting diode package according to the present invention includes a ceramic substrate having a mounting portion of the LED element on the upper surface and a wiring conductor; An LED element mounted on the mounting portion and electrically connected to the wiring conductor; Wherein the outer peripheral portion of the ceramic substrate top surface are joined so as to surround the mounting portion, the inner peripheral surface is included in the is a reflecting surface metal reflector that reflects light emitted from the LED element, the metal reflection plate is PbO, SiO _2, B ₂ O _3, the glass by the bonding layer containing TiO ₂ is bonded to the ceramic substrate. Preferably, the glass bonding layer comprises 70 to 80% by weight of PbO, 10 to 20% by weight of SiO ₂ , 5 to 10% by weight of B ₂ O ₃ , and TiO ₂ . 5 to 10% by weight.

According to an embodiment of the present invention, the glass bonding layer may further include calcium carbonate, sodium carbonate, barium carbonate, potassium carbonate and Al ₂ O ₃ .

According to the embodiment of the present invention, the wiring conductor may be made of Ag or a conductor containing Ag as a main component. The wiring conductor may extend from an upper surface of the substrate to a lower surface of the substrate through a via hole formed in the substrate.

According to an embodiment of the present invention, the ceramic substrate may be made of a ceramic material including Al ₂ O ₃ or AlN. For example, the ceramic substrate may be formed of an alumina-based sintered body containing Al ₂ O ₃ as a main component.

According to an embodiment of the present invention, the metal reflector may include one or more metals or alloys selected from the group consisting of Fe, Ni, Co, Cu, Al, and combinations thereof. Preferably, the metal reflector comprises an alloy of Fe, Ni and Co.

According to the embodiment of the present invention, it may further include a metal layer formed between the ceramic substrate and the glass bonding layer. The metal layer may include a metal selected from the group consisting of Ag, Cu, and Al. Preferably, the metal layer is made of the same material as the wiring conductor. For example, the metal layer and the wiring conductor may be made of a metal material containing Ag.

According to the exemplary embodiment of the present invention, the light-transmitting molding member may be further included on the inner side of the metal reflector to wrap the LED device. As this light-transmitting molding member, an epoxy resin or a silicone resin can be used, for example. In addition, the light transmitting molding member may include a phosphor. In addition, a translucent cover such as a flat plate shape or a lens shape may be bonded onto the metal reflecting plate.

In order to achieve another object of the present invention, a method of manufacturing a light emitting diode package according to the present invention, comprising the steps of preparing a ceramic substrate having a mounting portion of the LED element on the upper surface; Mounting an LED element on the mounting portion and electrically connecting the wiring conductor; Bonding a metal reflector having a through hole to an outer circumference of the ceramic substrate using a glass paste comprising PbO, SiO ₂ , B ₂ O ₃ , TiO ₂ . The glass paste may further include calcium carbonate, sodium carbonate, barium carbonate, potassium carbonate and Al ₂ O ₃ .

According to an embodiment of the present invention, the ceramic substrate may be formed of a ceramic material including Al ₂ O ₃ or AlN. In addition, the metal reflector may be formed to include at least one metal or alloy selected from the group consisting of Fe, Ni, Co, Cu, Al, and a combination thereof.

According to an embodiment of the present invention, the bonding of the metal reflecting plate may include applying the glass paste to one or both surfaces of the bonding surface of the metal reflecting plate and the ceramic substrate; Pressing the metal reflecting plate and the ceramic substrate with the coated glass paste interposed therebetween; The adhesive may include heat treating the resultant to cure the adhesive part. In this case, preferably, the curing step, the heat treatment in a reducing atmosphere at a temperature of 300 to 500 ℃.

According to the above embodiment, the method may further include forming a metal layer on an outer circumferential portion of the substrate before applying the glass paste. Preferably, the metal layer is formed of the same material as the wiring conductor. For example, the metal layer and the wiring conductor may be simultaneously formed by firing Ag paste at a high temperature.

According to an exemplary embodiment of the present invention, after the bonding of the metal reflecting plate, the method may further include forming a translucent molding member in the through hole to wrap the LED device.

In addition, according to an embodiment of the present invention, the method may further include bonding a transparent cover such as a flat plate shape or a lens shape to the upper surface of the metal reflecting plate.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

2 is a side sectional view showing an LED package 100 according to an embodiment of the present invention. Referring to FIG. 2, the LED package 100 includes a ceramic substrate 101 and a metal reflector plate 104. Wiring conductors 102a and 102b are formed on an upper surface of the ceramic substrate 101, and the wiring conductors 102a and 102b extend to the lower surface of the substrate 101 through via holes formed in the substrate 101. In addition, the ceramic substrate 101 has a mounting portion 20 of the LED element 108 on its upper surface. The through hole 104a is formed in the metal reflecting plate 104, and the inner peripheral surface thereof forms the reflecting surface 104b. The reflecting surface 104b serves to reflect the light emitted from the LED element 108 upwards. The LED element 108 is fixed to the mounting portion 20 on the wiring conductor 102a formed in the mounting portion 20, and is electrically connected to the wiring conductor 102b through the bonding wire 109. In the inside of the metal reflecting plate 104 (in the through hole 104a), the light-transmitting molding part 105 made of a silicone resin or the like encloses the LED element 108. The light-transmitting molding part 105 may include a phosphor for wavelength converting the light emitted by the LED element 108.

The wiring conductors 102a and 102b may be made of Ag or a conductor containing Ag as a main component. For example, the Ag paste may be printed on the substrate 101 and then fired at a high temperature to form the wiring conductors 102a and 102b. In addition, the ceramic substrate 101 may be made of a ceramic material including Al ₂ O ₃ or AlN. For example, the ceramic substrate 101 may be formed of an alumina-based sintered body containing Al ₂ O ₃ as a main component.

The metal reflector plate 104 may include a metal or an alloy selected from at least one selected from the group consisting of Fe, Ni, Co, Cu, Al, and a combination thereof. Preferably, the metal reflector is made of an alloy of Fe, Ni, and Co. As such an alloy, an alloy commercially available under the trade name KOVAR can be used.

As shown in FIG. 2, the metal reflecting plate 104 is bonded to the outer circumferential portion of the ceramic substrate 101 to surround the mounting portion 20. This metal reflecting plate 104 is bonded to the ceramic substrate 101 by the glass bonding layer 113. This glass bonding layer 113 is a sintered body of glass paste that can be obtained or manufactured at a much lower price than a conventional Au-Sn solder. The glass and the bonding layer 113 may include _{PbO, SiO 2, B 2 O} 3 and TiO _2. In addition to these main components, calcium carbonate, sodium carbonate, barium carbonate, potassium carbonate and Al ₂ O ₃ may be further included in the glass bonding layer 113 to enhance thermal and chemical stability. Preferably, the glass bonding layer 113 includes 70 to 80% by weight of PbO, 10 to 20% by weight of SiO ₂ , and 5 to 10% by weight of B ₂ O ₃ , TiO ₂ in an amount of 5 to 10% by weight. The glass bonding layer 113 has a thermal expansion coefficient of 1 ppm / K or less, which is lower than that of Au-Sn solder. Therefore, the thermal stability of the glass bonding layer 113 is superior to the conventional Au-Sn solder.

The inventor confirmed that the glass bonding layer 113 exhibits high bonding strength. 7 is an optical micrograph showing a cross section of an interface portion of the ceramic substrate 101 and the glass bonding layer 104 of the LED package manufactured according to the embodiment. As shown in FIG. 7, almost no gap is visible at the interface between the ceramic substrate 101 and the glass bonding layer 113 to provide a penetration path of moisture to reduce the bonding force. As a result of the actual shear strength test, when the Al ₂ O ₃ based sintered body was used as the ceramic substrate 101 and the alloy of Fe, Ni and Co (KOVAR) was used as the metal reflecting plate 104, the glass bonding layer was used. Reference numeral 113 indicates sufficient bonding strength that is comparable to or higher than that of conventional Au-Sn solders. Since the glass bonding layer 113 has a low coefficient of thermal expansion compared to a conventional Au-Sn solder, temperature stability is better than that of the conventional Au-Sn solder. In addition, since the low cost glass bonding layer is used to bond the reflecting plate 104 and the substrate 101, the manufacturing cost of the light emitting diode package is significantly reduced.

3 is a side cross-sectional view of a light emitting diode package 200 according to another embodiment of the present invention. Referring to FIG. 3, in the LED package 200, a metal layer 113 is formed between the ceramic substrate 101 and the glass bonding layer 113. The light emitting diode package 200 of the present embodiment is the same as the light emitting diode package 100 of the above-described embodiment except that the metal layer 111 is further included.

The metal layer 111 may include a metal selected from the group consisting of Ag, Cu, and Al. Preferably, the metal layer 111 is made of the same material as the wiring conductors 102a and 102b. For example, the metal layer 111 and the wiring conductors 102a and 102b may be made of a sintered body of Ag paste.

4 is a side cross-sectional view of a light emitting diode package 300 according to another embodiment of the present invention. Referring to FIG. 4, a transparent cover 120 is bonded to the metal reflector plate 120. The transparent cover 120 serves to protect the LED device 108. In addition, the transparent cover 120 may be an optical element having a predetermined optical characteristic. For example, a concave lens or a convex lens may be used as the transparent cover 120. In addition, a transparent cover 120 made of a flat glass substrate may be used.

In the above-described embodiments, the LED element 108 is bonded onto the wiring conductor 102a of the junction portion 20 and connected to the wiring conductor 102b through the wire 109, thereby providing the wiring conductors 102a and 102b. Was electrically connected to. However, as another alternative, the LED element may be electrically connected to the package wiring through two wires. An example of this is shown in FIG. 5.

Referring to FIG. 5, the LED element 108 ′ mounted on the mounting portion 20 ′ is electrically connected to the wiring conductors 102a ′ and 102 b ′ through two wires 109 ′ and 109 ″. . In this case, the LED element 108 ′ corresponds to a horizontal LED element. Since the mounting portion 20 'does not provide electrical connection, the LED element 108' can be fixedly bonded to the mounting portion 20 'via an insulator bonding material (not shown). Alternatively, the LED element 108 'may be connected to the wiring conductor by flip chip bonding.

Hereinafter, a method of manufacturing a light emitting diode package according to an embodiment of the present invention will be described with reference to FIGS. 6A to 6E. In this embodiment, the manufacturing method of the package 100 of FIG. 2 or the package 300 of FIG. 4 is demonstrated. However, it will be apparent to those skilled in the art that the package 200 of FIG. 3 or the package 400 of FIG. 5 may be manufactured through appropriate modifications or additions.

First, referring to FIG. 6A, a ceramic substrate 101 having a mounting portion 200 of an LED element on the top surface and having wiring conductors 102a and 102b formed thereon is prepared. Materials of the wiring conductors 102a and 102b and the ceramic substrate 101 may be selected as described above.

Next, as shown in FIG. 6B, the LED element 108 is bonded and fixed on the mounting portion 20, and the wiring conductor 102b and the LED element 108 are electrically connected through the wire 109. Accordingly, the LED element 108 is mounted on the substrate 101.

Next, as shown in Figure 6c, using a glass paste containing PbO, SiO ₂ , B ₂ O ₃ , TiO ₂ , a metal reflector plate 104 having a through hole 104a is used for the ceramic substrate 101. ) To the outer circumference of the

Specifically, the glass paste is first applied to one or both surfaces of the bonding surface of the metal reflector plate 104 and the ceramic substrate 101. Thereafter, the metal reflecting plate 104 and the ceramic substrate 101 are press-bonded with the coated glass paste interposed therebetween. Thereafter, the bonded result is heat treated at a temperature of 300 to 500 ° C. to cure the adhesive part. In order to prevent the metal reflector 104 from being oxidized during the heat treatment, the heat treatment is performed in a reducing atmosphere (eg, nitrogen and hydrogen gas atmosphere). Accordingly, the metal reflector plate 104 is bonded to the ceramic substrate 101 with strong bonding strength. The inner circumferential surface of the bonded metal reflecting plate 104 forms a reflecting surface 104b. The glass paste may further include calcium carbonate, sodium carbonate, barium carbonate, potassium carbonate and Al ₂ O ₃ . In order to manufacture the package 300 of FIG. 3, the metal layer 111 may be formed on the outer circumferential portion of the ceramic substrate 101 before applying the glass paste. In this case, the metal layer 111 is formed of the same material as the wiring conductors 102a and 102b. For example, the metal layer 101 and the wiring conductors 1012a and 102b may be simultaneously formed by firing Ag paste at a high temperature.

Next, as illustrated in FIG. 6D, a light-transmitting molding member 105 made of epoxy or silicone resin is formed in the through hole 104a to wrap the LED device 108. Thereafter, a translucent cover 120 such as a flat plate shape or a lens shape is bonded to the upper surface of the metal reflecting plate 104 as necessary (see FIG. 6E). As a result, a light emitting diode package having excellent bonding strength between the metal reflecting plate 104 and the ceramic substrate 101 is obtained.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. In addition, it will be apparent to those skilled in the art that the present invention may be substituted, modified, and changed in various forms without departing from the technical spirit of the present invention described in the claims.

As described above, according to the present invention, by using the glass bonding layer having excellent bonding strength, it is possible not only to implement a highly reliable light emitting diode package but also to greatly reduce the manufacturing cost of the light emitting diode package. In addition, by using the glass bonding layer having a low coefficient of thermal expansion, it is possible to improve the thermal stability of the light emitting diode package.

Claims (25)

A ceramic substrate having a mounting portion and a wiring conductor of an LED element formed on an upper surface thereof; An LED element mounted on the mounting portion and electrically connected to the wiring conductor; A metal reflecting plate bonded to an outer circumferential portion of the upper surface of the substrate so as to surround the mounting portion, the inner circumferential surface being a reflecting surface reflecting light emitted from the LED element, The metal reflector is bonded to the ceramic substrate by a glass bonding layer containing PbO, SiO ₂ , B ₂ O ₃ and TiO ₂ . The method of claim 1, The glass bonding layer contains 70 to 80% by weight of PbO, 10 to 20% by weight of SiO ₂ , 5 to 10% by weight of B ₂ O _3, and 5 to 10% by weight of TiO ₂ . A light emitting diode package comprising a%. The method of claim 1, The glass bonding layer further comprises calcium carbonate, sodium carbonate, barium carbonate, potassium carbonate and Al ₂ O ₃ . The method of claim 1, The wiring conductor is a light emitting diode package, characterized in that consisting of Ag or a conductor containing Ag as a main component. The method of claim 1, The ceramic substrate is a light emitting diode package, characterized in that made of a ceramic material containing Al ₂ O ₃ or AlN. The method of claim 1, The metal reflector plate comprises a metal or alloy selected from the group consisting of Fe, Ni, Co, Cu, Al and combinations thereof. The method of claim 1, The metal reflector is a light emitting diode package comprising an alloy of Fe, Ni and Co. The method of claim 1, The light emitting diode package further comprises a metal layer formed between the ceramic substrate and the glass bonding layer. The method of claim 8, The metal layer is a light emitting diode package comprising a metal selected from the group consisting of Ag, Cu and Al. The method of claim 8, The metal layer is a light emitting diode package, characterized in that the same material as the wiring conductor. The method of claim 10, The metal layer and the wiring conductor is a light emitting diode package, characterized in that made of a metal containing Ag. The method of claim 1, The light emitting diode package further comprises a translucent molding member installed to package the LED element inside the metal reflector. The method of claim 12, The light emitting diode package, characterized in that the transparent molding member contains a phosphor. The method of claim 1, The light emitting diode package further comprises a transparent cover bonded to the metal reflector. Preparing a ceramic substrate having a mounting portion of an LED element on an upper surface thereof and having a wiring conductor formed thereon; Mounting an LED element on the mounting portion and electrically connecting the wiring conductor; And Bonding a metal reflecting plate having a through hole to an outer circumference of the ceramic substrate using a glass paste including PbO, SiO ₂ , B ₂ O ₃ and TiO ₂ as a bonding material, In the step of bonding the metal reflector, the metal reflector is bonded to surround the mounting portion manufacturing method of a light emitting diode package. The method of claim 15, The glass paste further comprises a calcium carbonate, sodium carbonate, barium carbonate, potassium carbonate and Al ₂ O ₃ manufacturing method of a light emitting diode package. The method of claim 15, The ceramic substrate is a method of manufacturing a light emitting diode package, characterized in that formed of a ceramic material containing Al ₂ O ₃ or AlN. The method of claim 15, The metal reflecting plate, Fe, Ni, Co, Cu, Al and a method of manufacturing a light emitting diode package, characterized in that it comprises a metal or alloy selected from the group consisting of a combination thereof. The method of claim 15, Bonding the metal reflecting plate, Applying the glass paste to one or both surfaces of a bonding surface of the metal reflector and the ceramic substrate; Pressing the metal reflective plate and the ceramic substrate with the coated glass paste interposed therebetween; And And heat-treating the bonded resultant to cure the adhesive part. The method of claim 19, The curing step, the method of manufacturing a light emitting diode package comprising the step of heat treatment in a reducing atmosphere at a temperature of 300 to 500 ℃. The method of claim 19, And forming a metal layer on an outer circumferential portion of the substrate before applying the glass paste. The method of claim 21, And the metal layer is formed of the same material as the wiring conductor. The method of claim 22, The metal layer and the wiring conductor are formed by firing Ag paste at the same time. The method of claim 15, And after the bonding step of the metal reflecting plate, forming a translucent molding member in the through hole to wrap the LED element. The method of claim 15, The method of manufacturing a light emitting diode package comprising the step of bonding a transparent cover to the upper surface of the metal reflector.

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